As disclosed by Jang in the U.S. Pat. No. 4,959,053, an improved device for use in controlling the intravenous drip comprises a cap 2 having a horizontally oriented round tubular hole 23 in which a ring 25 is movably disposed. The movement of the ring 25 is movably disposed. The movement of the ring 25 in the round tubular hole 23 facilitates an entry of the air into the solution bottle via an air passage 28 so as to maintain a constant air pressure in the solution bottle. In order to safeguard a patient receiving the intravenous drip and to avert any possible mishap that might be brought about by a human negligence, the device described above is further provided with a dripping vessel 1 having therein a valve 4 capable of rising and descending along with the level of the solution contained in the dripping vessel 1. As a result, whenever the solution is about to be used up, the valve 4 descends to a level at which a conical surface 42 of the valve 4 is caused to obstruct the passage of the solution through a connecting tube 3, thereby bringing about an automatic interruption of the intravenous drip. Such a prior art device as described above is defective in design in that the dripping vessel 1 must be pressed and squeezed with the hands each time when the solution bottle of the intravenous drip is replaced, so as to force the air remaining in the dripping vessel 1 to flow into the new solution bottle. Without such a maneuver, the intravenous drip can not be resumed. It must be noted here that the job of pressing and squeezing the dripping vessel 1 must be done repeatedly by a skilled medical personnel. In addition, the prior art device for use in controlling the intravenous drip is generally devoid of the valve capable of automatically interrupting the intravenous drip. Therefore, a petient receiving the intravenous drip is often subjected to a mishap in which the air is permitted accidentally to enter the connecting tube or the body of the patient at such time when the solution in the solution bottle is exhausted. Moreover, whenever the solution bottle is replaced, the solution remaining in the connecting tube must be forced back into the solution bottle by shaking the device; otherwise the hypodermic needle must be removed from the patient and then injected hypodermically into the patient again.